It drove me nuts to disable the automatic spell checking on text input fields in Mac OS X again and again to make that red lines going away on technical terms or other stuff not known by the spell checker.

Thankfully I found a post at which describes how to permanently disable automatic spell checking on Mac OS X.

I was going one step further and disabled all languages by renaming the whole Resources directory:

sudo mv /System/Library/Services/AppleSpell.service/Contents/Resources \

and creating an empty directory:

sudo mkdir /System/Library/Services/AppleSpell.service/Contents/Resources

Warning: Don’t touch your system that way if you don’t know what the meaning of the commands above is.

Nohw I’m frie tu wreite as I wand!

Update 2019: Last I checked the directory still exists at macOS 10.14.